Issue link: https://iconnect007.uberflip.com/i/1372612
MAY 2021 I PCB007 MAGAZINE 69 ed by ISO inspectors. You need specific details and not generalities. Also, most companies think that since they have IPC standards, that is all they need. No, it's not. Having chaired a half-dozen IPC docu- ments over the years, IPC standards are trying to solve world hunger. What I mean by that is: IPC standards are general in nature to incor- porate requirements for all applications. As a company, you are concerned only about your products and applications, so therefore, you need to have your own requirements. Yes, you can use IPC standards where it meets your re- quirements. In addition, IPC standards are not specifica- tions. Specifications are written by the compa- ny that writes the checks. at means you. You need to have custom documents to meet your product requirements based on the market that you serve. You do need IPC standards but use them as a guideline to develop your own customized process and design document. Training Having the right design, good quality incom- ing materials, and an in-house process docu- ment are necessary but not sufficient. Training of personnel at all levels, from senior managers to engineers, operators and purchasing agents is critical for addressing all the issues needed to improve yield. No one gets up in the morning and says, "I am going to screw up three things today." So, it is management's responsibility to provide training at all levels. Again, training is one area where you will see a wide variation in different companies. And what do you need to train your personnel? You need the three documents I discussed earlier. e documents are developed by a few engineers in the com- pany. ey know what is in those documents. You need to use those documents to develop your training program and spread the knowl- edge about those documents across all your employees who need to know. In addition to leading the SMT team, one of my roles at Intel decades ago was to train engi- neers (with the help of many of my colleagues). My job was to develop those documents and teach the classes. I did this one every quarter for five years. A Case Study Here is another point worth keeping in mind: Even when a board is designed by the custom- er and built at different locations of the same company, the quality results can be vastly dif- ferent. And the quality results are also different when the same board is built by different com- panies. Let me give you a real-life example. I served as a technical expert in a large le- gal tax case between the IRS and a major U.S. OEM involving a $1 billion tax liability. e case lasted over two years and was finally tried in U.S. tax court; the IRS lost the case. In the case, the OEM designed the board in the U.S. and built it overseas in its own subsidiary. ey also built the same board at different EMS companies in the U.S. and paid about the same amount for assembly of those boards to all the suppliers, including their own subsidiary. However, the IRS had a problem with the OEM paying the same amount to its own subsid- iary as what it had paid to its U.S. suppliers. Ac- cording to the IRS, the OEM should have been paying less to its own subsidiary since it was in a low-cost country. According to the IRS, the only reason they were paying an excessive amount to their subsidiary was because the OEM wanted to reduce their profit in the U.S. where profit is taxable, while increasing and their profit over- seas where there is no tax on profit. e IRS had two reasons for their argument: the subsidiary was in a low-cost country, and the board was designed in the U.S. e IRS as- serted that DFM is the key to quality, basing this on my book, SMT Principles and Practice. As design was the difficult part of the process, manufacturing cost should have been deter- mined essentially by the labor cost. Well, the OEM was not just going to write them a check for $1 billion in back taxes, so they sued the IRS. e only reason I got in-